Frost dates for 99611Kenai, AK
The average last spring frost in Kenai is May 24 and the average first fall frost is September 12, giving a typical growing season of about 110 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 24
- Average first fall frost
- Sep 12
- Growing season
- 110 days
Safer after Jun 4 (1-in-10 risk)
Possible by Aug 29 (1-in-10 risk)
Last frost typically in 209 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | — | — | 74 days | 100% |
| Frost / freeze (32°F) | May 8 · May 24 · Jun 4 | Aug 29 · Sep 12 · Sep 27 | 110 days | 100% |
| Hard freeze (28°F) | Apr 22 · May 5 · May 18 | Sep 7 · Sep 25 · Oct 10 | 142 days | 100% |
Planting calendar for Kenai
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 23 – Jun 29 |
| Tomatoes | Transplant outdoors | Jun 9 – May 23 |
| Peppers | Start seeds indoors | Apr 23 – May 24 |
| Peppers | Transplant outdoors | Jun 23 – Jul 24 |
| Eggplant | Start seeds indoors | May 10 – Jun 8 |
| Eggplant | Transplant outdoors | Jun 23 – Jul 24 |
| Cucumbers | Sow outdoors | Jun 23 – Jun 2 |
| Summer squash | Sow outdoors | Jun 9 – Jul 24 |
| Winter squash & pumpkins | Sow outdoors | Jun 23 – Jul 24 |
| Snap beans | Sow outdoors | Jun 9 – Jun 25 |
| Sweet corn | Sow outdoors | Jun 9 – May 23 |
| Watermelon & cantaloupe | Sow outdoors | Jun 23 – Jul 24 |
| Okra | Sow outdoors | Jun 16 – Jul 9 |
| Peas | Sow outdoors (spring) | Apr 23 – Jun 8 |
| Potatoes | Plant outdoors (spring) | Apr 23 – Jun 23 |
| Onions | Start seeds indoors (spring) | Mar 12 – Apr 8 |
| Onions | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (spring) | Apr 5 – May 9 |
| Broccoli | Transplant outdoors (spring) | May 10 – Jun 8 |
| Broccoli | Start seeds indoors (fall) | May 13 – May 23 |
| Broccoli | Transplant outdoors (fall) | Jun 12 – Jun 23 |
| Cabbage | Start seeds indoors (spring) | Mar 26 – Apr 23 |
| Cabbage | Transplant outdoors (spring) | Apr 23 – May 24 |
| Cabbage | Start seeds indoors (fall) | May 3 – Jun 2 |
| Cabbage | Transplant outdoors (fall) | Jun 2 – Jul 3 |
| Leaf lettuce | Sow outdoors (spring) | Apr 23 – Jul 9 |
| Leaf lettuce | Sow outdoors (fall) | Jun 2 – Jul 19 |
| Spinach | Sow outdoors (spring) | Apr 16 – May 30 |
| Spinach | Sow outdoors (fall) | Jun 19 – Jul 24 |
| Radishes | Sow outdoors (spring) | Apr 23 – Jun 13 |
| Radishes | Sow outdoors (fall) | Jun 2 – Aug 3 |
| Kale | Sow outdoors (spring) | May 10 – May 30 |
| Kale | Sow outdoors (fall) | May 26 – Jul 3 |
| Carrots | Sow outdoors (spring) | May 24 – Jul 9 |
| Carrots | Sow outdoors (fall) | May 3 – Jun 18 |
| Garlic | Plant outdoors (fall) | Sep 2 – Oct 3 |
Where these dates come from
ZIP code 99611 is matched to the NOAA station Kenai Muni Ap, AK, 4 km away, at 91 ft elevation (21 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Kenai Muni Ap, AK (used) | 91 ft | May 24 | Sep 12 |
| Kenai 9N, AK | 126 ft | May 18 | Sep 22 |
| Soldotna 5Ssw, AK | 180 ft | Jun 11 | Sep 1 |
| Sterling 6Sw, AK | 292 ft | May 20 | Sep 21 |
Frost dates near Kenai
- Nikiski, AK 99635 · last May 18, first Sep 22
- Soldotna, AK 99669 · last Jun 11, first Sep 1
- Sterling, AK 99672 · last May 20, first Sep 21
- Kasilof, AK 99610 · last Jun 11, first Sep 1
- Clam Gulch, AK 99568 · last Jun 11, first Sep 1
- Tyonek, AK 99682 · last May 18, first Sep 22
- Ninilchik, AK 99639 · last May 10, first Sep 29
- Anchor Point, AK 99556 · last May 27, first Sep 22
Frequently asked questions
- When is the last frost in Kenai, AK?
- For ZIP code 99611, the average last spring frost (32°F) is May 24, based on NOAA 1991-2020 climate normals for the Kenai Muni Ap, AK weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Kenai, AK?
- The average first fall frost (32°F) is September 12. There is a 1-in-10 chance of frost by August 29, so tender plants are at risk from that point on.
- How long is the growing season in 99611?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 110 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.